Description: The United States has charged that the Soviet Union is implicated in the use of chemical weapons in Afghanistan and of chemical and toxin weapons, including the toxin known as "Yellow Rain," in Laos and Kampuchea (Cambodia). These charges raise two significant sets of issues: First, issues surrounding the evidence that has been presented to show: (a) that such weapons have been used and (b) that the Soviet Union is implicated in this use. Second, issues connected with the implications of Soviet involvement, if proven, in chemical and toxin warfare.